Fuel injector with a metering assembly having a seat secured to polymeric support member that is secured to a polymeric housing with a guide member and a seat disposed in the polymeric support member

ABSTRACT

A fuel injector is described that includes a polymeric housing, pole piece, filter assembly, coil assembly, spring member, armature assembly and metering assembly. The housing has a passageway extending between an inlet opening and an outlet opening along a longitudinal axis. The pole piece is disposed in the passageway and has a through opening. The filter assembly has a portion disposed in the through opening of the pole piece. The coil assembly is disposed in the housing to surround the pole piece. The spring member is disposed partly in the pole piece and includes a spring portion contiguous with the portion of the filter assembly. The armature assembly is disposed in the passageway in a first position confronting the end face of the pole piece and in a second position contiguous to an end face of the pole piece. The metering assembly is disposed proximate the outlet opening and includes a seat and a polymeric support member secured to the polymeric housing.

PRIORITY

This application claims the benefits under 35 U.S.C. § 119 based onProvisional Application Ser. No. 60/531,206, entitled “Plastic BodiedFuel Injector,” and filed on Dec. 19, 2003, which application isincorporated herein in its entirety into this application.

BACKGROUND OF THE INVENTION

Examples of known fuel injection systems use an injector to dispense aquantity of fuel that is to be combusted in an internal combustionengine. The quantity of fuel that is dispensed is varied in accordancewith a number of engine parameters such as engine speed, engine load,engine emissions, etc.

Known electronic fuel injection systems monitor at least one of theengine parameters and electrically operate the injector to dispense thefuel. It is believed that examples of known injectors useelectro-magnetic coils, piezoelectric elements, or magnetostrictivematerials to actuate a valve.

A known fuel injector utilizes a plethora of internal components such asa metallic inlet tube connected to a valve body via a non-magnetic shellwith a pole piece interposed therebetween. The inlet tube, valve body,non-magnetic shell and pole piece are generally affixed to each otherafter a closure assembly and a metering assembly are disposed in thevalve body. A solenoid coil is inserted over the assembled componentsand the entire assembly is molded into the fuel injector.

It is believed that one known fuel injector utilizes a plastic bodymolded over a solenoid coil to provide a plastic inlet fuel passage witha metallic valve body being coupled to the solenoid coil.

It is believed that another known fuel injector utilizes two separatesubassemblies to form the fuel injector. The first subassembly caninclude a complete coil assembly and electrical connector molded into anouter casing to provide a power group. The second subassembly caninclude an inlet tube, pole piece, non-magnetic shell valve body,closure assembly and metering assembly affixed together to form a standalone fuel group. The two sub-assemblies are formed separately andcoupled together to provide an operable fuel injector.

While the known fuel injectors are suited to the task of metering fuel,it is believed that the known fuel injectors may have certain assemblyor component drawbacks that require extensive manufacturing process tobe undertaken to ensure that the injector are suitable for commercialapplications. They can include, for example, the necessity for multipleseal points between components to provide leak integrity in the injectorand a large number of manufacturing steps that are undertaken. Theseseals can be effectuated by elastomeric seals, such as, O-rings, ormultiple hermetic welds to ensure structural and leak integrity of theknown fuel injectors. Others include the potential manufacturingdifficulties associated with thermal distortion in welding multiplemetallic components at close proximity to each other or the need for ametal valve body with internal resilient seals for leak integrity. Yetanother drawback can include the utilization of lift setting componentsthat must be inserted into the valve body of the fuel injector. Thus, itwould be advantageous to reduce or even eliminate some of thesedrawbacks.

SUMMARY OF THE INVENTION

The present invention provides for, in one aspect, a fuel injector thatis believed to reduce or eliminate these drawbacks of the known fuelinjectors while maintaining substantially the same operativeperformance. The fuel injector of the present invention utilizes aminimal number of seal points and is designed so that an interfacebetween a potential leak point is hermetically sealed by apolymer-to-polymer seal.

According to one aspect of the present invention, the fuel injectorincludes a polymeric housing, pole piece, filter assembly, coilassembly, spring member, armature assembly and metering assembly. Thehousing has a passageway extending between an inlet opening and anoutlet opening along a longitudinal axis. The pole piece is disposed inthe passageway and has a through opening. The filter assembly has aportion disposed in the through opening of the pole piece. The coilassembly is disposed in the housing to surround the pole piece. Thespring member is disposed partly in the pole piece and includes a springportion contiguous with the portion of the filter assembly. The armatureassembly is disposed in the passageway in a first position confrontingthe end face of the pole piece and in a second position contiguous to anend face of the pole piece. The metering assembly is disposed proximatethe outlet opening and includes a seat and a polymeric support member.The polymeric support member is secured to the polymeric housing.

In yet another aspect, a fuel injector is provided. The fuel injectorincludes a polymeric housing, pole piece, filter assembly, coilassembly, spring member, armature assembly, metering assembly and aguide member. The housing has a passageway extending between an inletopening and an outlet opening along a longitudinal axis. The outletopening includes a rim disposed about the longitudinal axis. The polepiece is disposed in the passageway and has a through opening. Thefilter assembly has a portion disposed in the through opening of thepole piece. The coil assembly is disposed in the polymeric housing tosurround the pole piece. The spring member is disposed partly in thepole piece and includes a spring portion contiguous with the portion ofthe filter assembly. The armature assembly is disposed in the passagewayin a first position confronting the pole piece and in a second positioncontiguous to an end face of the pole piece. The armature assembly has aclosure member reciprocable along the longitudinal axis. The meteringassembly has a seat surface secured to a polymeric support member. Thepolymeric support member includes an outer pocket surrounding a portionof the rim, and a central pocket having a boss located in the centralpocket and about the longitudinal axis. The guide member is disposed inthe central pocket. The guide member includes a base portion contiguousto the boss to locate the base portion with respect to the seat surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate an embodiment of the invention,and, together with the general description given above and the detaileddescription given below, serve to explain the features of the invention.

FIG. 1 is a cross-sectional representation of a fuel injector accordinga preferred embodiment.

FIG. 2 is a perspective view of a polymeric support member including aguide member and a metering orifice of the fuel injector of FIG. 1.

FIG. 3 is a cross-sectional representation of a fuel injector accordinganother preferred embodiment.

FIG. 4 is a cut-away perspective view of a metering assembly including aguide member for the fuel injector of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-4 illustrate the preferred embodiments of a fuel injector 100 or200. Referring to FIGS. 1 and 3, the fuel injector 100 or 200 includes acontinuous polymeric housing 10 extending from an inlet 12 to an outlet14 along a longitudinal axis A-A. The polymeric housing 10 includes apolymeric wall surface or bore 10A that directly faces the longitudinalaxis A-A to define a passage 16 in which fuel can flow from the inlet12. The passage 16 includes the polymeric bore 10A that extends from afirst external seal 20 proximate the inlet 12 to a second external seal22 proximate an outlet 14 along the longitudinal axis A-A. Disposedwithin a portion of the polymeric bore 10A is a metering assembly 24proximate the second external seal 22. A closure assembly 26 is disposedproximate the metering assembly 24, which is coupled to a rim portion 28at the outlet end 14 of the polymeric housing 10. A portion of theclosure assembly 26 is disposed in the polymeric bore 10A and betweenthe first and second external seals 20, 22. The passage 16 can bedefined by a plurality of diameters for the polymeric bore 10A. Thepolymeric bore 10A can also include an inward (i.e., towards thelongitudinal axis A-A) surface to define a guide surface 36 for areciprocable closure member. The inward surface preferably includes aconvex surface. The polymeric housing 10 can be formed from a suitablepolymeric material such as, for example, Nylon 6-6 with about 30 percentglass filler.

As shown in FIGS. 1 and 3, the polymeric housing 10 provides a completesolenoid coil subassembly that is ready for assembly with the meteringand closure assemblies. In particular, the polymeric housing 10 includesa solenoid coil assembly 38 disposed within the polymeric housing 10 sothat no part of the coil assembly 38 extends outside the boundary of thepolymeric housing 10. The solenoid coil assembly 38 is connected to atleast one electrical terminal 40 formed on an electrical connectorportion 42 of the polymeric housing 10. The terminal 40 and theelectrical harness connector portion 42 can engage a mating connector,e.g., part of a vehicle wiring harness (not shown), to facilitateconnecting the injector 100 or 200 to an electrical power supply (notshown) for energizing the electromagnetic coil 48.

The coil assembly 38 includes a coil housing 44 disposed about thelongitudinal axis A-A to surround a bobbin 46 and at least one wirecoiled about the bobbin 46 to form an electromagnetic coil 48. The coilhousing 44, which provides a return path for magnetic flux, generallytakes the shape of a ferro-magnetic cylinder surrounding theelectromagnetic coil 48. A flux washer 50 can abut a top surface of thebobbin 46 so that the flux washer 50 is in physical contact with thecoil housing 44. The flux washer 50 can be integrally formed with orseparately attached to the coil housing 44. The coil housing 44 caninclude holes, slots, or other features to break up eddy currents, whichcan occur when the coil 48 is de-energized.

The coil assembly 38 can be preferably constructed as follows. A plasticbobbin 46 is molded with at least one electrical contact extending fromthe bobbin 46 so that the peripheral edge of the contact can be matedwith a contact terminal for electrical communication between the coiland a power source. A wire for the electromagnetic coil 48 is woundaround the plastic bobbin 46 a predetermined number of times andconnected to the at least one electrical contact portion. Theelectromagnetic coil 48 (with bobbin 46) is placed into the coil housing44. An electrical terminal, which is pre-bent to a desired geometry, isthen electrically connected to each electrical contact portion providedon the bobbin 46. Thereafter, the polymeric housing 10 can be formed bya suitable technique such as, for example, thermoset casting,compression molding or injection molding. The polymeric housing 10,e.g., an overmold, provides a structural casing for the injector 100 or200 and provides predetermined electrical and thermal insulatingproperties. In a preferred embodiment, the polymeric housing 10 isformed by injection molding around the coil assembly 38 and theelectrical connector, i.e., an insert-molding so that the meteringassembly can be affixed to the polymeric housing 10. The insert-moldinghermetically seals the coil assembly 38 from contamination with fuelflow through the polymeric fuel passage 16.

Referring to FIGS. 1 and 3, the metering assembly 24 includes a seat 24Athat can be any suitable material such as, for example, plastic, ceramicor metal, long as it provides a suitable sealing surface. In thepreferred embodiments, the seat 24A is formed of metallic material, andis secured to a polymeric support member 24B with an O-ring 30 or a tab29 disposed circumferentially about the seat 24A. Preferably, themetallic seat 24A is a stainless steel seat. That is, as the seat 24Aand its O-ring 30 or tab 29 are insert-molded, the O-ring or tab iscaptured between the seat 24A and the polymeric molding material that,upon curing of the polymeric material, becomes the polymeric supportmember 24B. The O-ring 30 or tab 29 is believed to seal the interfacebetween dissimilar materials being insert-molded. Consequently, in theevent that thermal cycling could cause separation in the interfacebetween the metallic seat and the polymeric support member, the O-ring30 or tab 29 would be able to maintain a seal therebetween.

The metallic seat 24A defines a seat orifice 24H generally centered onthe longitudinal axis A-A and through which fuel can flow into theinternal combustion engine (not shown). The seat 24A includes a sealingsurface 24S surrounding the seat orifice 24H. The sealing surface, whichfaces the interior of the passage 16, can be frustoconical or concave inshape, and can have a finished or coated surface.

Referring to FIGS. 1 and 2, the support member 24B includes a firstpocket 24C defined by a cylindrical portion to receive a cup-shapedguide member 24E. The cup-shaped guide member 24E can be formed from asuitable material such as, for example, polymeric, ceramic or metallic.Preferably, the guide member 24E is stamped metallic member press-fittedinto the first pocket 24C to a predetermined location with respect tothe seat 24A via boss extension 24G formed in the first pocket 24C. Thecup-shaped guide member 24E includes an aperture disposed about thelongitudinal axis A-A and at least one aperture offset with respect tothe longitudinal axis A-A. The support member 24B also includes a secondpocket 24D defined by an annular cylindrical portion. The second pocket24D is configured to receive the rim portion 28 of the outlet 14 of thepolymeric housing 10. Preferably, the second pocket 24D is configured sothat at least a locational clearance fit to a light press-fit is formedbetween the rim portion 28 of the polymeric housing 10 and the innerwall surface 24F of the annular cylinder and the outer surface 25A ofthe inner cylinder of the first pocket 24C.

In the embodiment of FIGS. 3 and 4, the polymeric support member 24Bwith a tab 29 is disposed circumferentially around the perimeter of theseat 24A. The seat 24A and its tab 29 are insert-molded so that the tab29 is captured between the seat 24A and the polymeric molding material.Upon curing of the polymeric material, the polymeric molding materialbecomes the polymeric support member 24B. The polymeric support member24B includes an outer cylindrical wall surface 25A and an innercylindrical wall surface 25B. The distal end of polymeric support member24B, proximate to the outlet 14, includes an annulus or slot 25C that isorientated generally perpendicular to the longitudinal axis A-A. Theslot 25C receives the tab 29 of the metering disc 24I as shown in FIG.3. The outer cylindrical wall surface 25A of the polymeric supportmember 24B, as shown in FIGS. 3 and 4, is preferably configured toprovide a suitable fit, e.g., locational to light press fit, with theinner surface of the polymeric bore 10A.

The cylindrically shaped polymeric support member 24B may receive thecup-shaped guide member 24E. The guide member 24E can be formed from asuitable material such as, for example, polymeric, ceramic or metallic.Preferably, the guide member 24E is a stamped metallic memberpress-fitted into the inner cylindrical wall surface 25B to apredetermined location with respect to the seat 24A.

In FIGS. 1-4, the guide member 24E includes a cylindrical wall portion24E2, a base portion 24E5, a center aperture 24E1, and at least oneoffset aperture 24E6. The wall portion 24E2 has an outer wall surface24E3 and an inner wall surface 24E4. The outer wall surface 24E3 iscontiguous with a portion of the inner cylindrical wall surface 25B ofthe polymeric support member 24B. The base portion 24E5 is preferablydisc-shaped and extends substantially perpendicular to the wall portion24E2. The center of the base portion 24E5 is generally aligned with thelongitudinal axis A-A of the fuel injector.

At the center of the base portion, the aperture 24E1 is disposed aboutthe longitudinal axis A-A. The aperture 24E1 is sufficiently largeenough to allow the maximum diameter of the closure member 26E to passthrough it and to guide the closure member along the longitudinal axisA-A between its open and close positions.

The apertures 24E6 are preferably offset with respect to thelongitudinal axis A-A and may be located around the perimeter of thebase portion 24E5. Because the base portion 24E5 is preferablydisc-shaped, the offset apertures at the perimeter may be a compoundcurved opening. The offset apertures 24E6, however, can be any suitableshape that effectively allows fuel to communicate from the passage 16 tothe seat surface 24S.

A metering disc 24I can be used in connection with the seat 24A toprovide at least one precisely sized and oriented metering orifice 24Jin order to obtain a particular fuel spray pattern. The precisely sizedand oriented metering orifice 24J can be disposed on the center axis ofthe metering disc 24I or, preferably, the metering orifice 24J candisposed off-axis, and oriented in any desirable angular configurationrelative to one or more reference points on the fuel injector 100 or200.

Referring to FIGS. 1 and 3, the closure assembly 26 includes a polepiece 26A and an armature assembly 26B configured to be magneticallycoupled to the solenoid coil assembly 38 in a fully assembled fuelinjector 100 or 200. The pole piece 26A can be formed as a cylindricalcomponent with a passage 26A1 extending through the pole piece 26A. Thepole piece 26A can be formed by a suitable technique such as cast,machined, pin rolled with external barbs or a combination of thesetechniques. The pole piece passage 26A1 includes a resilient member 27disposed in the pole piece passage 26A1. The outer surface of the polepiece 26A can be provided with recesses or projections 26A2 to assist inretention of the pole piece 26A once the pole piece 26A has beenpress-fitted to a desired location in the polymeric bore 10A as shown inFIG. 1.

A filter assembly 52 with a filter element 52A and an adjusting tube 52Bis also disposed in the polymeric bore 10A. As shown in FIGS. 1 and 3,the filter assembly 52 includes a first end and a second end. A gap isprovided along a central portion of the filter assembly 52. Theadjusting tube 52B is partially disposed in the pole piece passage 26A1at the second end of the filter assembly 52 provided with a passage 18.The adjusting tube 52B engages the resilient member 27 and adjusts thebiasing force of the resilient member 27 with respect to the pole piece26A. The filter element 52A is retained at the first end of the filterassembly 52 spaced from the adjusting tube 52B portion and outside ofthe pole piece passage 26A1 so that the gap between the filter assembly52 and the polymeric bore 10A is provided therebetween. In the preferredembodiments, the adjusting tube 52B provides a reaction member againstwhich the resilient member 27 reacts in order to close the armatureassembly 26B when the solenoid coil assembly 38 is de-energized. Theposition of the adjusting tube 52B can be retained with respect to thepole piece 26A or the polymeric housing 10 by an interference fitbetween an outer surface of the adjusting tube 52B and an inner surfaceof the pole piece passage 26A1. Thus, the position of the adjusting tube52B with respect to the pole piece 26A can be used to set apredetermined dynamic characteristic of the armature assembly 26B.

Referring to FIG. 1, the armature assembly 26B includes an armature 26Csecured to an elongated member 26D, which is secured to a closure member26E. The closure member 26E can be of any suitable shape, such as, forexample, cylindrical, semi-spherical or spherical. In the case of aspherical shaped closure member 26E, i.e., a spheroidal member, thespheroidal member can be connected to the elongated member 26D at adiameter that is less than the diameter of the spheroidal member. Such aconnection would be on side of the spheroidal member that is oppositecontiguous contact with the seat 24A.

As noted earlier, the armature lower guide 24E can be disposed in thefirst pocket 24C of the polymeric support member 24B, proximate the seat24A, and would slidingly engage the outer surface of the sphericalclosure member as shown in FIG. 1. The lower armature lower guide 24Ecan facilitate alignment of the armature assembly 26B along thelongitudinal axis A-A, and can reduce flux leakage to the closure member26E.

Alternatively, the armature assembly 26B can be formed by securing anarmature 26C directly to the closure member 26E, as shown in FIG. 3. Thearmature 26C may be secured to the closure member 26E by a weld W1. Atleast one aperture 26F can be formed through a wall of the armature 26C.The apertures 26F, which can be of any shape, are preferablynon-circular, e.g., axially elongated, to facilitate the passage of gasbubbles. For example, in the case of a separate armature tube that isformed by rolling a sheet substantially into a tube, the apertures canbe an axially extending slit defined between non-abutting edges of therolled sheet. However, the apertures 26F, in addition to the slit, wouldpreferably include openings extending through the sheet. The apertures26F provide fluid communication between the armature passage 26G and thefuel outlet 14.

The closure member 26E is movable between a closed configuration, asshown in FIGS. 1 and 3, and an open configuration (not shown). In theclosed configuration, the closure member 26E contiguously engages a seatsurface of the metallic seat 24A to prevent fluid flow through the seatorifice 24H. In the open configuration, the closure member 26E is spacedfrom the seat surface to permit fluid flow through the seat orifice 24H.

A radial end face 26I of the armature 26C is configured to contact aradial end face 26J of the pole piece 26A when the armature 26C is movedby magnetic flux generated by the solenoid coil assembly 38. In theembodiment illustrated in FIG. 1, the armature 26C is provided with adeep counterbore 26H to receive the other end of the preload resilientelement 27. In the embodiment illustrated in FIG. 3, no counterbore 26His provided and the end of the resilient element 27 is configured toabut the radial end face 26I of the armature 26C.

In the preferred embodiments illustrated in FIGS. 1 and 3, surfacetreatments can be applied to at least one of the end face of the polepiece 26A or the armature 26C to improve the armature's response, reducewear on the impact surfaces and variations in the working air gapbetween the respective end faces. The surface treatments can includecoating, plating or case-hardening. Coatings or platings can include,but are not limited to, hard chromium plating, nickel plating orkeronite coating. Case hardening on the other hand, can include, but arenot limited to, nitriding, carburizing, carbo-nitriding, cyaniding,heat, flame, spark or induction hardening.

The surface treatments will typically form at least one layer ofwear-resistant materials on the respective end faces. These layers,however, tend to be inherently thicker wherever there is a sharp edge,such as between junction between the circumference and the radial endface of either portions. Further, this thickening effect results inuneven contact surfaces at the radially outer edge of the end portions.However, by forming the wear-resistant layers on at least one of the endfaces, where at least one end portion has a surface generally oblique tolongitudinal axis A-A, both end faces can be substantially in evencontact with respect to each other when the solenoid coil assembly 38 isenergized.

Since the surface treatments may affect the physical and magneticproperties of the ferromagnetic portion of the armature assembly 26B orthe pole piece 26A, a suitable material, e.g., a mask, a coating or aprotective cover, surrounds areas other than the respective end facesduring the surface treatments. Upon completion of the surfacetreatments, the material is removed, thereby leaving the previouslymasked areas unaffected by the surface treatments.

In the preferred embodiment illustrated in FIG. 3, the armature 26C isformed by stamping a cylindrical workpiece of substantially constantthickness into the final configuration shown herein. As a function ofthe stamping process, a cylinder end portion is rolled inward so that anannular end face 26I is formed with an outer edge 26K being imbued witha radiused surface of curvature. This allows a surface coating to beformed on the radiused surface such that the coating is thicker at thejunction between the radiused surface and the outer cylindrical wallsurface of the armature 26C. By having a thicker coating at thisjunction, the contact between the end faces of the pole piece 26A andthe armature 26C is believed to be in substantially even contact witheach other. It should be noted that the respective wall thickness of theend face 26I and a sidewall 26M are substantially the same for thestamped armature 26C. Alternatively, the armature 26C can be formed bydeep drawing a generally flat workpiece through a suitable die.

Although both embodiments illustrate an armature 26C of about the samelength, other lengths (e.g., shorter or longer) can be provided byimplementing a different length elongated member 26D and correspondingpolymeric housing 10 in the embodiment of FIG. 1 or a different lengthstamped armature 26C and corresponding polymeric housing 10 in theembodiment of FIG. 3. As utilized, the armature 26C is a ferromagneticmember.

According to the preferred embodiments, the magnetic flux generated bythe electromagnetic coil 48 flows in a circuit that includes the polepiece 26A, the armature assembly 26B, the coil housing 44, and the fluxwasher 50. The magnetic flux moves along the coil housing 44 to the baseof the coil housing 44, through the polymeric housing 10 across a radial(relative to axis A-A) or parasitic airgap to the armature 26C, andacross an axial (relative to axis A-A) or working air gap towards thepole piece 26A, thereby lifting the armature 26C and closure member 26Eoff the seat 24A. Furthermore, since the armature 26C is partly withinthe interior of the electromagnetic coil 48, the magnetic flux isbelieved to be denser, leading to a more efficient electromagnetic coil48. In the embodiment of FIG. 1, the ferro-magnetic closure member 26Eis magnetically decoupled from the armature 26C via the non-magneticelongated member 26D, which reduces flux leakage of the magneticcircuit, thereby improving the efficiency of the electromagnetic coil48.

In the preferred embodiments, the fuel injector 100 or 200 can beassembled as follows. A polymeric fuel injector body 10 with aninsert-molded solenoid coil assembly 38 is provided, as shown in FIGS. 1and 3. The metering assembly 24 is fitted into the polymeric bore 10A ofthe outlet 14 of the polymeric housing 10 and these components are thensecured to each other by a suitable technique such as, for example, UVlight activated adhesive, thermal bonding, or laser welding to form ahermetic seal HW. In the preferred embodiments, the metering assembly 24is secured to the outlet by a suitable structural adhesive or by laserwelding. For example, as shown in FIG. 3, a suitable radiant energy beammay be passed through the rim portion 28 to the outer cylindrical wallsurface 25A of the polymeric support member 24B, at which point theouter surface of the rim portion 28 begins to melt under radiant energybeam. The melting of the outer surface of the rim portion 28 is believedto cause the outer cylindrical wall surface 25A to also begin melting,which leads to a fused portion of polymeric materials provided by therim portion 28 and the outer cylindrical wall surface 25A. As thecomponents and the radiant energy source are rotated relative to eachother, the fused portion forms a continuous seam, which provides ahermetic seal HW at the interface of the rim portion 28 and the outercylindrical wall surface 25A against a flow of fuel in the polymericbore 16. Details of the technique to form the hermetic seal HW viaadhesive or laser welding are also disclosed in copending U.S. patentapplication Ser. No. 11/014,693, entitled “Method of Plastic Bonding APlastic Fuel Component to Another Plastic Fuel Component,” filed on thesame date as this application, which copending application isincorporated herein by reference in its entirety into this application.

The armature assembly 26B is inserted into the polymeric bore 10A forcontiguous engagement with the metering assembly 24, which form a valveassembly that regulates flow of fuel from the fuel injectors 100 and200. The pole piece 26A is press-fitted to a predetermined locationwithin the polymeric bore 10A so that a lift distance (i.e., thedistance the armature assembly 26B travels to close a working air gapwith the pole piece 26A) of the armature assembly 26B is defined by thispredetermined location. The resilient element 27 is inserted into thepole piece passage 26A1 so that one end contiguously engages the closureassembly. The filter assembly 52 is press-fitted into the pole piecepassage 26A1 so that the second end of the filter assembly 52 preloadsthe resilient element 27 against the armature assembly 26B to providefor the closure assembly 26. The external seals, preferably Viton typeO-rings, are installed on recessed portions proximate the inlet 12 andoutlet 14 of the fuel injector 100 or 200. At this point, the fuelinjector 100 or 200 is ready to be calibrated before being tested. Thecalibration can involve modifying the preload force of the resilientelement 27 such as, for example, by repositioning the adjustingtube/filter assembly 52 along axis A-A while flowing fuel through thefuel injector 100 or 200 to achieve a desired opening time for theclosure member 26E. Subsequently, the fuel injector 100 or 200 can betested (e.g., flow or leak testing) prior to being shipped to customers.

In operation, the electromagnetic coil 48 is energized, therebygenerating magnetic flux in the magnetic circuit. The magnetic fluxmoves armature assembly 26B (along the axis A-A, according to apreferred embodiment) towards the pole piece 26A to close the workingair gap. This movement of the armature assembly 26B separates theclosure member 26E from the seat 24A and allows fuel to flow from thefuel rail (not shown), through the polymeric inlet bore passage 16, thepole piece passage 26A1, the through-bore 26G of the armature 26C, theapertures 26F to between the seat 24A and the closure member 26E,through the seat orifice 24H, and finally through the metering disc 24Iinto the internal combustion engine (not shown). When theelectromagnetic coil 48 is de-energized, the armature assembly 26B ismoved by the bias force of the resilient member 27 to contiguouslyengage the closure member 26E with the seat 24A, and thereby preventfuel flow through the injector 100 or 200.

Details of the preferred embodiments are also described in the followingcopending applications: (1) “Polymeric Bodied Fuel Injector,” Ser. No.11/014,694; (2) “Method of Polymeric Bonding Fuel System Components,”Ser. No. 11/014,693; (3) “Polymeric Bodied Fuel Injector With A ValveSeat And Elastomeric Seal Molded To A Polymeric Support Member” Ser. No.11/014,692; (4) “Fuel Injector With A Metering Assembly Having A SeatMolded to A Polymeric Support Member,” Ser. No. 11/014,691; (5) “FuelInjector With A Metering Assembly Having At Least One Annular RidgeExtension Between A Valve Seat and A Polymeric Valve Body,” Ser. No.11/014,699; (6) “Fuel Injector With An Armature Assembly Having AContinuous Elongated Armature And A Metering Assembly Having A Seat AndPolymeric Support Member,” Ser. No. 11/014,698; (7) “Fuel Injector WithA Metering Assembly Having A Polymeric Support Member Which Has AnExternal Surface Secured To A Bore Of A Polymeric Housing And A GuideMember That Is Disposed In The Polymeric Support Member,” Ser. No.11/014,695; (8) “Fuel Injector With A Metering Assembly With A PolymericSupport Member And An Orifice Disk Positioned A Terminal End Of ThePolymeric housing,” Ser. No. 11/014,696; and (9) “Method ofManufacturing Polymeric Fuel Injectors,” Ser. No. 11/015,032, which areincorporated herein by reference in their entireties into thisapplication.

While the present invention has been disclosed with reference to certainembodiments, numerous modifications, alterations and changes to thedescribed embodiments are possible without departing from the sphere andscope of the present invention, as defined in the appended claims.Accordingly, it is intended that the present invention not be limited tothe described embodiments, but that it has the full scope defined by thelanguage of the following claims, and equivalents thereof.

1. A fuel injector comprising: a polymeric housing having a passagewayhaving a plurality of different diameters extending between an inletopening and an outlet opening along a longitudinal axis; a pole piecedisposed in the passageway, the pole piece having a through opening; anarmature assembly disposed in the passageway in a first positionconfronting the pole piece and in a second position contiguous to aportion of an end face of the pole piece, the armature assembly having aclosure member; and a metering assembly having a seat and a polymericsupport member, the seat being supported relative to the polymerichousing by the polymeric support member, the polymeric support memberbeing secured to the polymeric housing proximate the outlet; a filterassembly having a portion disposed in the through opening of the polepiece; a coil assembly disposed in the polymeric housing to surround thepole piece; a spring member disposed partly in the pole piece andincluding a spring portion contiguous with the portion of the filterassembly, wherein the passageway comprises a projection that extendstowards the longitudinal axis to define a guide surface, the guidesurface contiguous to the first portion of the second wall of thearmature assembly.
 2. The fuel injector of claim 1, wherein thepolymeric housing comprises a substantially nylon body enclosing thecoil assembly, the nylon body including an electrical connector.
 3. Thefuel injector of claim 2, wherein the coil assembly comprises a coilhousing surrounding a bobbin provided with multiple coil windings, thecoil housing contiguous to a flux washer disposed generally orthogonalto the longitudinal axis, the multiple coil windings electricallyconnected to terminals provided on the electrical connector.
 4. A fuelinjector comprising: a polymeric housing having a passageway extendingbetween an inlet opening and an outlet opening along a longitudinalaxis, the outlet opening including a rim disposed about the longitudinalaxis; a pole piece disposed in the passageway, the pole piece having athrough opening; a filter assembly having a portion disposed in thethrough opening of the pole piece; a coil assembly disposed in thepolymeric housing to surround the pole piece; a spring member disposedpartly in the pole piece and including a spring portion contiguous withthe portion of the filter assembly; an armature assembly disposed in thepassageway in a first position confronting the pole piece and in asecond position contiguous to an end face of the pole piece, thearmature assembly having a closure member reciprocable along thelongitudinal axis.
 5. The fuel injector of claim 4, wherein the guidemember comprises a metallic guide member.
 6. The fuel injector of claim5, wherein the guide member comprises a wall portion having a generallycylindrical outer surface contiguous to the inner surface of the centralpocket and generally parallel to the longitudinal axis.
 7. The fuelinjector of claim 6, wherein the central pocket comprises a generallycylindrical wall that extends over a first length along the longitudinalaxis, the cylindrical wall having an inner surface disposed at an insideradius from the longitudinal axis.
 8. The fuel injector of claim 7,wherein the guide member comprises a wall having a second length ofabout ⅓ the first length along the longitudinal axis.
 9. The fuelinjector of claim 8, wherein the outer surface of the guide membercomprises an outer surface located at an outer radius from thelongitudinal axis at least equal to the inside radius of the polymericsupport member.
 10. The fuel injector of claim 9, wherein the guidemember comprises a guide member press-fitted into the pocket of thepolymeric support member.
 11. The fuel injector of claim 10, wherein thearmature assembly comprises a first wall having a first surfaceconfronting the end face of the pole piece and a second wall extendingalong the longitudinal axis, the first and second walls havingsubstantially the same thickness, the first surface including agenerally planar surface and a coating disposed on at least one of theplanar surface and the end face of the pole piece.
 12. The fuel injectorof claim 11, wherein the first wall comprises a first through openingextending through the first wall to define an annulus.
 13. The fuelinjector of claim 12, wherein the second wall comprises at least asecond through opening extending through the second wall, the at leastsecond through opening in fluid communication with the first throughopening.